Risedronate is a nitrogen-containing bisphosphonate with a high affinity for hydroxyapatite crystals in bone, and for the resorption surfaces of bone. Risedronate is a potent inhibitor of osteoclasts and a potent antiresorptive agent. This study is designed to assess the efficacy and safety of a once-weekly dosing regimen of Risedronate as compared to a daily dosing regimen as the active control in post-menopausal women with osteoporosis. Efficacy will be assessed by percent changes in lumbar spine bone mineral density at one year. Once a week dosing is anticipated to increase convenience for the patient, thereby improving compliance. The GCRC will be utilized for outpatient visits of up to 1 hour and for phlebotomy and processing of specimens.